Would we ignore its great economical and environmental value and use it as a massive natural landfill? If previous generations had begun this practice, would we stand by as the canyon was filled up with garbage?

I'm sure we wouldn't.

So, why are we idly, negligently watching the steady destruction of the Weeki Wachee River?

No, the Weeki Wachee doesn't have the Grand Canyon's stature as an international treasure, but it's the closest thing to it in Hernando.

It's the landmark you probably use when you try to tell out-of-town friends where you live, the place you probably take them if you want to blow them away with an example of local beauty.

And, if allowing excess fertilizers from lawns and golf courses to seep into the spring-fed river is not quite as willfully destructive as dumping garbage, the damage it causes is almost as glaringly ugly.

Also, the way to start righting this wrong — passing a reasonable fertilizer ordinance — is almost as obvious.

So why haven't we done it?

That's what I kept asking myself last week after attending two events sponsored by the Hernando Audubon Society, which plans to present a proposed fertilizer ordinance to the County Commission in April.

The first get-together, on Thursday, featured Harley Means of the Florida Geological Survey. Means spoke about the sad state of the state's magnificent springs, including the Weeki Wachee, which he called "one of the poster children for increased nitrates.''

Since 1970, the concentration of this nutrient has climbed from just above zero to about 1 milligram per liter — roughly twice the level measured just 12 years ago when the Southwest Florida Water Management District completed its first study on the problem.

Nitrates feed the clots of Lyng­bya algae, the hairlike green stuff that has replaced snow-white sand and eel grass as the backdrop of the mermaid performances at Weeki Wachee Springs.

Along the length of the river, algae has choked out native plants that support fish and other wildlife species, making for a generally more sterile ecosystem. The damage extends to the estuaries and maybe even into the Gulf of Mexico. Studies have linked fertilizer-loaded runoff with increasingly severe and long-lasting outbreaks of red tide.

And, unfortunately, there's no soothing natural explanation for the increased nitrate levels in the Weeki Wachee.

No doubt about it: We're to blame.

Chemical markers in the river's nitrates link them indisputably to chemical fertilizers, according to Swiftmud. And Means displayed a graph that showed nitrates in the Weeki Wachee had increased at almost exactly the same pace as the county's population — and the accompanying proliferation of St. Augustine lawns and Bermuda fairways.

"That's a pretty good correlation, wouldn't you say?'' Means said as he looked at the graph.

As if I needed more proof of the river's declining health, I joined Audubon members on a birding outing on the Weeki Wachee the following day.

It's still beautiful, of course. Moments after putting in downstream from the spring, I saw the mirage you can see nowhere else in the county: water so clear the kayaks appeared to be floating in air.

We saw great blue and little blue herons, and an eagle's white head protruding from a nest roughly the size of the Swiss Family Robinson's tree house.

But, Audubon members said, compared to trips in previous years, the number and variety of birds they counted was disappointingly small.

And the outing's organizer, Vera Huckaby, was able to confirm the accuracy of those early images of mermaids, the ones showing them drifting though gracefully waving grass and the masses of fish usually associated with pristine coral reefs.

Huckaby, a mermaid from 1962 to 1967, remembers the river was at least a foot deeper then, with a bed of white sand rather than green Lyngbya, and far more mullet and bass — and even massive garfish that sometimes appeared in the mermaid arena.

Even if we took radical action now, it might be years before the load of already-applied fertilizer worked its way down through the soil and into the aquifer.

Still, an ordinance would help.

The version Audubon members are preparing will be based on existing laws in Lee and Sarasota counties. These ban fertilizer applications during the summer rainy seasons and on the edges of lakes and rivers. They limit the amount of fertilizer that can be applied, especially quick-release varieties that quickly percolate through the soil and into the aquifer.

The effort will no doubt face opposition from landscapers and maybe even home builders. But the main enemy to the environment is excessive fertilizer use, and that is what these ordinances address, said Phil Compton of the Sierra Club office in St. Petersburg.

Lawns and golf courses in Sarasota are still green two years after the law passed, he said, and some landscapers and homeowners report saving money on fertilizer and the labor of frequent applications.

So, it doesn't force us to part with our beloved St. Augustine lawns. Not yet. Though if it ever comes to that, I know which side I'm on. A beautiful river or a fibrous, artificial hybrid grass that depends on regular doses of fertilizer and pesticides?

There is a reason why the air in Tampa Bay is filled with playoff talk. If Thursday night's 12-8 Bucs preseason win over the Jaguars is any indication, it's also going to be filled with footballs thrown by quarterback Jameis Winston.